I’ve noticed that one reason people don’t buy more champagne or sparkling wine is that they often feel obligated to drink the entire bottle. With a still wine, you can just put the cork back in, but with sparkling wines, there are the bubbles to worry about.
There’s actually nothing to fear — all you need is a good champagne stopper. At home (alone, alas), I typically drink half a bottle of champagne a day (I’m not nearly as big a lush as some people believe), and save the other half for the next day. This is partly to moderate my consumption, but more importantly, I find that many young champagnes are actually more interesting after being opened for a day. Even when I owned a wine bar, I was never afraid to pour champagnes by the glass, as I found that young champagnes could easily last two or sometimes even three days if properly stoppered (although between the guests and the staff, they rarely lasted that long!)
There are several different types of inexpensive stoppers available. In the photo above, the big blue one at the top is the simplest model: you push it down and little teeth inside grasp the edge of the bottle. Going clockwise, the next one is slightly more sophisticated: you push it down and screw it shut, ensuring a better seal. Less aesthetically attractive but perhaps even more efficacious is the clamp model, with a hinged clip that grabs the neck of the bottle, keeping the whole thing firmly in place. (By the way, this is the only one that works on certain irregularly shaped bottles, such as Dom Pérignon or Comtes de Champagne. Not that, you know, we’re putting stoppers on those every day.) Then there’s the bright blue thing that looks like a UFO — it has two arms that swing down to grasp the bottle. My favorite one, however, and the one that I use most often, is the last, which has a tight, spring-loaded rubber seal and two little flanges on the hinged portions that grip the lip of the bottle. Plus it’s made of shiny metal and it’s pretty. You can find these at most wine stores or order them easily online.